1. Field of the Invention
This invention pertains to electrical instrumentation. More specifically, this invention pertains to electro-optical instrumentation. In greater particularily, this invention pertains to photo-electric analysis of gas mixtures. By way of further characterization this invention concerns photo-electric smoke transducers. In still greater particularity this invention will be described as it relates to smoke transducers for aircraft cockpit interiors.
2. Description of the Prior Art
The design of modern aircraft and other vehicles requires the application of many disciplines. In order to make the vehicle as safe as possible, consideration must be given to fire hazards and the possibility of escape in the event of fire. A major problem exists in configuring and placing vital instruments and operational controls where they may be located and seen by operational personnel in the event of fire and the attendant reduction in visibility caused by smoke and heat turbulence. In the close confines of a military aircraft or a naval vessel it is necessary, therefore, to know the density of smoke as a function of time-after-ignition at various points in the vehicle interior. With this knowledge, vital instruments and controls may be placed in locations affording the longest time of visibility thereby facilitating escape and survival of operational personnel.
Of course, in the optical instrumentation arts the photo-electric measurement of smoke and gas turbulency has become commonplace and a well defined subclass of instruments are known for this purpose. However, these instruments are generally large and permanently installed in fixed positions. For effective use in smoke and atmospheric measurements in confined spaces, a transducer must effectively sample a small portion of the ambient space without either responding to other portions of the volume or inhibiting the normal gas flow within the volume. Heretofore, no instrument was sufficiently small, responsive to a limited portion of a larger volume, and heat resistant enough to reliably gather data for vehicle fires.